Abstract

Background: Histamine intolerance is thought to trigger manifold clinical symptoms

after ingesting histamine-rich food due to reduced activity of diamine oxidase

(DAO). No study has hitherto systematically assessed daily fluctuations of histamine

levels and DAO activities in symptomatic patients. The aim of the study was to

investigate the presence of histamine intolerance, to therefore establish day profiles

of histamine levels and DAO activities, and to compare the results between patients

with suspected histamine intolerance, food allergy and healthy controls.

Methods: We determined day profiles of histamine plasma levels and DAO serum

activities in 33 patients with suspected histamine intolerance, in 21 patients with

proven food allergy and in 10 healthy control patients. Clinical symptoms, food

intolerances and further clinical and laboratory chemical parameters were evaluated.

Results: Twenty-four percent (8 of 33) suspected histamine-intolerant patients

showed elevated histamine levels during the day. That might be caused by constantly

and significantly reduced DAO activities in these patients compared to foodallergic

and control patients. The remaining 25 patients presented normal histamine

levels and DAO activities, but an increased prevalence of multiple food intolerances

compared to the other subgroup of suspected histamine-intolerants. There was no

correlation between subjective complaints and serological histamine parameters in

patients with suspected histamine intolerance.

Conclusions: We determined by daily profiling that decreased DAO activities

correlated with elevated histamine levels in a subgroup of suspected histamineintolerants.

This finding discriminates these patients from food intolerant individuals

with similar clinical symptoms and strongly suggests the presence of histamine

intolerance.